In order to function effectively the scraper blade must be urged against the belt with a suitable force determined by the properties of the blade, the belt, and the material to be scraped, so that optimum scraping is obtained consistent with satisfactorily low rate of wear of the blade and resistance to and damage to the belt. At the same time the scraper should be at least partly automatically adjustable so that, as the blade wears in use, it remains in satisfactory engagement with the belt. In one known system a counterbalance arrangement is used. This arrangement, while generally effective as regards the force with which the blade is urged against the belt, tends to be relatively expensive and bulky so that it may be difficult to fit within a conveyor apparatus. In another system a series of vertically arranged coiled metal springs is used. This arrangement, while more compact than the counterbalance arrangement, has a limited range of automatic self-adjustment. Adjustments can be made, but jamming of the adjustment mechanism is a problem in certain environments. In yet another system the blade is rotationally mounted for movement about an axis spaced from the belt and perpendicular to the direction of motion of the belt. The blade is biased by metal springs or elastomer buffers against the belt to absorb shocks and to follow the motion of the belt. Again the range of automatic adjustment is limited and jamming of the setting mechanism is a frequent problem in practice.
Accordingly this invention seeks to provide a belt scraper that satisfactorily ameliorates the above mentioned disadvantages, while permitting safe and relatively quick adjustment when required.